Ever-increasing quality for stored video streaming in a mobile wireless interworking environment

ABSTRACT

There is provided a method for managing the downloading and display of a video program using a mobile device in an networking environment that includes a first radio access network and a second radio access network that has a faster transfer rate than the first network. A layer of video program that has been encoded into multiple layers is downloaded via the first or second network. The downloaded video program is displayed at a playback rate that corresponds to a display quality. Excess portion of the downloaded video program that result when a rate at which the video program is displayed are buffered. The number of layers being downloaded and the playback rate at which the video program is displayed are increased to increase the display quality, when the buffered excess portions exceeds a threshold level.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to downloading and displaying avideo program from networks and, more particularly, to a method and amobile terminal for downloading and displaying a video program by themobile device in an interworking environment comprising a first radioaccess network having a first data transfer rate and a second radioaccess network having a second data transfer rate that is faster thanthe first data transfer rate.

2. Background of the Invention

In an interworking that includes two networks such as, for example, aThird Generation (3G) cellular network and a Wireless Local Area Network(WLAN), it is desirable to take advantage of the increased bandwidth ofthe faster network (e.g., the WLAN) to download and display higherquality video whenever a mobile terminal enters the coverage area of thefaster network.

For video streaming, there are currently two main approaches to make useof the higher bandwidth. The first approach is to switch between a highdisplay rate and a low display rate when a mobile terminal moves in andout of a higher bandwidth coverage area. The second approach is to keepa constant low display rate even in the higher bandwidth coverage area.

The end result of the first approach is actually very annoying to mobileusers, especially for relatively high mobility usage scenarios. Userswould rather maintain a constant quality than frequently switch theirquality perception levels. The second approach maintains the same lowdisplay quality, but it does not take full advantage of the higherbandwidth coverage area.

Accordingly, it would be desirable and highly advantageous to have amethod and mobile terminal capable of taking advantage of increasedbandwidth in an interworking environment, while overcoming theabove-described deficiencies of the prior art.

SUMMARY OF THE INVENTION

The problems stated above, as well as other related problems of theprior art, are addressed by the present invention, which is directed toa method and mobile terminal for managing the downloading and display ofa video program by the mobile terminal in an interworking environment.The present invention takes advantage of the increased bandwidthprovided in higher bandwidth areas of the interworking environment toincrease the number of layers being downloaded and to increase theplayback rate so as to increase the video display quality.

According to an aspect of the present invention, there is provided amethod for managing the downloading and display of a video program usinga mobile device in an interworking environment. The interworkingenvironment includes a first radio access network having a first datatransfer rate and a second radio access network having a second datatransfer rate that is faster than the first data transfer rate. A layerof a video program that has been encoded into multiple layers isdownloaded via the first or second radio access networks, such that thevideo program is downloaded at the faster data transfer rate when themobile terminal is in the coverage area of the second radio accessnetwork. The downloaded video program is displayed at a playback ratethat corresponds to a display quality. Excess portions of the downloadedvideo program that result when a rate at which the video program isbeing downloaded exceeds a rate at which the video program is displayedare buffered. The number of layers being downloaded and the playbackrate at which the video program is displayed are increased to increasethe display quality, when the buffered excess portions of the downloadedvideo program exceeds a threshold level.

According to another aspect of the present invention, there is provideda mobile terminal for managing the downloading and display of a videoprogram in an interworking environment. The interworking environmentincludes a first radio access network having a first data transfer rateand a second radio access network having a second data transfer ratethat is faster than the first data transfer rate. A receiver downloads,via the first or second radio access networks, a layer of a videoprogram encoded into multiple layers. The video program is downloaded atthe faster data transfer rate when the mobile terminal is in thecoverage area of the second radio access network. A display displays thedownloaded video program at a playback rate that corresponds to adisplay quality. A memory device buffers excess portions of thedownloaded video program that result when a rate at which the videoprogram is being downloaded exceeds a rate at which the video program isdisplayed. A processor increases the number of layers being downloadedand the playback rate at which the video program is displayed to therebyincrease the display quality, when the buffered excess portions of thedownloaded video program exceed a threshold level.

According to yet another aspect of the present invention, there isprovided a method for managing the downloading and display of a videoprogram using a mobile device in an interworking environment. Theinterworking environment includes a first radio access network having afirst data transfer rate and a second radio access network having asecond data transfer rate that is faster than the first data transferrate. A layer of a video program that has been encoded into multiplelayers is downloaded via the first or second radio access networks suchthat the video program is downloaded at the faster data transfer ratewhen the mobile terminal is in the coverage area of the second radioaccess network. The downloaded video program is displayed at a playbackrate that corresponds to a display quality. A current layer and the nextlayer of the video program is downloaded at the same time when themobile terminal enters the coverage area of the second radio accessnetwork, even if the current layer of the video program is still beingdownloaded. The playback rate at which the video program is displayed isincreased to increase the display quality, when the entire next layerhas been completely downloaded.

According to still yet another aspect of the present invention, there isprovided a mobile terminal for managing the downloading and display of avideo program using a mobile device in an interworking environment. Theinterworking environment includes a first radio access network having afirst data transfer rate and a second radio access network having asecond data transfer rate that is faster than the first data transferrate. A receiver downloads, via the first or second radio accessnetworks, a layer of a video program encoded into multiple layers. Thevideo program is downloaded at the faster data transfer rate when themobile terminal is in the coverage area of the second radio accessnetwork. The receiver further downloads a current layer and the nextlayer of the video program at the same time when the mobile terminalenters the coverage area of the second radio access network even if thecurrent layer of the video program is still being downloaded. A displaydisplays the downloaded video program at a playback rate thatcorresponds to a display quality, and increases the playback rate atwhich the video program is displayed to thereby increase the displayquality when the entire next layer has been completely downloaded.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a mobile terminal 100 to whichthe present invention may be applied according to an illustrativeembodiment of the present invention;

FIG. 2 is a block diagram illustrating an interworking environment 200to which the present invention may be applied according to anillustrative embodiment of the present invention;

FIG. 3 is a flowchart illustrating the steps for downloading anddisplaying a video program using a mobile terminal in an interworkingenvironment according to an illustrative embodiment of the presentinvention;

FIG. 4 is a diagram illustrating the downloading of a layered media withrespect to data transfer rate versus time, according to an illustrativeembodiment of the present invention;

FIG. 5 is a flowchart illustrating the steps for downloading anddisplaying a video program using a mobile terminal in an interworkingenvironment according to another illustrative embodiment of the presentinvention; and

FIG. 6 is a diagram illustrating the downloading of a layered media withrespect to data transfer rate versus time, according to anotherillustrative embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a method and a mobile terminal fordownloading and displaying a video program by the mobile device in aninterworking environment. The present invention takes advantage of theincreased bandwidth provided in higher bandwidth areas of theinterworking environment by increasing the number of layers of a videoprogram being downloaded as well as increasing the playback rate atwhich the video program is displayed so as to increase the displayquality. As used herein, the phrase “video program” refers to a programthat includes, at the least, video data, and may or may not also includeother data such as, for example, audio data.

To further explain the relation between the playback rate and thedisplay quality, the playback rate corresponds to the display quality inthat the playback increases for higher display qualities because alarger amount of data needs to be processed in a given amount of time.Conversely, the playback rate decreases for lower display qualitiesbecause a smaller amount of data needs to be processed in a given time.Thus, as used herein, the value of the playback rate at any given timegenerally relates to a corresponding display quality.

The present invention is applicable to video that has been encoded intomultiple layers. In general, the multiple layers include a base layerand at least one subsequent layer. As will be described below, eachlayer of a video program to be downloaded and displayed according to thepresent invention is associated with an incremental change to a playbackrate that corresponds to display quality. Thus, according to the presentinvention, a subsequent layer of a video program may be displayed usinga playback rate, or display rate, that is higher than a preceding layerof the video program. Examples of layered video media to which thepresent invention may be applied include, but are not limited to, MovingPictures Experts Group (MPEG) media, Joint Video Team (JVT) media, whichare well known to those skilled in the art.

In the illustrative embodiments described herein, the base layer of agiven layered media (e.g., video program) is larger than any of theadditional subsequent layers. Moreover, the size of each subsequentlayer is less than a preceding layer but more than a next layer. Suchlayered media is illustratively shown in FIGS. 4 and 6 that respectivelycorrespond to two illustrative embodiments of the present invention. Inparticular, FIGS. 3 and 4 correspond to a first illustrative embodimentof the present invention and FIGS. 5 and 6 correspond to a secondillustrative embodiment of the present invention. FIGS. 1 and 2generally apply to both illustrative embodiments of the presentinvention. However, it is to be appreciated that the present inventionis not limited to layered media arranged and structured as describedabove and, thus, layered media having other structures and arrangementsmay also be employed while maintaining the spirit and scope of thepresent invention. For example, the size of each subsequent layer neednot be less than a preceding layer nor more than a next layer.

It is to be understood that the present invention may be implemented invarious forms of hardware, software, firmware, special purposeprocessors, or a combination thereof. Preferably, the present inventionis implemented as a combination of hardware and software. Moreover, thesoftware is preferably implemented as an application program tangiblyembodied on a program storage device. The application program may beuploaded to, and executed by, a machine comprising any suitablearchitecture. Preferably, the machine is implemented on a computerplatform having hardware such as one or more central processing units(CPU), a random access memory (RAM), and input/output (I/O)interface(s). The computer platform also includes an operating systemand microinstruction code. The various processes and functions describedherein may either be part of the microinstruction code or part of theapplication program (or a combination thereof) that is executed via theoperating system. In addition, various other peripheral devices may beconnected to the computer platform such as an additional data storagedevice and a printing device.

It is to be further understood that, because some of the constituentsystem components and method steps depicted in the accompanying Figuresare preferably implemented in software, the actual connections betweenthe system components (or the process steps) may differ depending uponthe manner in which the present invention is programmed. Given theteachings herein, one of ordinary skill in the related art will be ableto contemplate these and similar implementations or configurations ofthe present invention.

The present invention is directed to an interworking environment. Suchan interworking environment may include, for example, ubiquitous lowspeed first radio access network and a second radio access networkhaving a much higher data transfer speed and lower access cost. Thepresent invention allows users with relatively high mobility to takefull advantage of such an environment in stored video streamingapplications.

Examples of low rate radio access networks to which the presentinvention may be applied (e.g., radio A above) include, but are notlimited to, fixed or mobile wireless wide area networks such as thirdgeneration (3G), second generation plus (2.5G), second generation (2G),and first generation (1G) cellular networks, and so forth. Examples ofhigh rate radio access networks to which the present invention may beapplied (e.g., radio B above) include, but are not limited to, WirelessLocal Area Networks (WLANs) and so forth. The WLANs may be, for example,those compliant with IEEE 802.11 or Hiperlan 2.

For ease of presentation, the following description of the presentinvention shall employ a 3G cellular network as radio A and a WLAN asradio B. However, it is to be appreciated that the present invention isnot limited to the preceding communication technologies and networktypes. Moreover, it is to be appreciated that the present invention maybe applied to an interworking between more than two networks whilemaintaining the spirit and scope of the present invention. Further, itis to be appreciated that the present invention may be applied to all ora subset of the networks that are part of an interworking whilemaintaining the spirit and scope of the present invention.

According to an illustrative embodiment of the present invention, amobile terminal downloads the video program at a higher data transferrate when occasionally passing through high-speed WLAN micro-cells. As aresult of the higher data transfer rate, excess portions of thedownloaded data is buffered in a memory device of the mobile terminal.In accordance with the present invention, when the amount of buffereddata exceeds a threshold level, the display quality of the video isincreased while ensuring that the display quality will never be degradedeven after the MT moves out of a WLAN cell. In particular, the thresholdlevel is determined based on the amount of playback time remaining inthe video program and the amount of data that can be downloaded duringthat time, even if the mobile terminal moves into the area of low datatransfer rate, such that the higher quality display can be maintainedbased on the buffered excess, the viewing time remaining and theadditional data that can be downloaded during the remaining viewingtime.

FIG. 1 is a block diagram illustrating a mobile terminal 100 to whichthe present invention may be applied, according to an illustrativeembodiment of the present invention. The mobile terminal 100 includes areceiver 110, a transmitter 120, a display 130, a memory 140, and aprocessor 150, all interconnected by a bus 179. The receiver 110 isconfigured to receive data from either one of the two radio accessnetworks. The mobile terminal may be, but is not limited to, a cellularphone, a Personal Digital Assistant (PDA), a laptop computer, and soforth. The arrangement and operation of such elements in those devicesare well known to those skilled in the art.

FIG. 2 is a block diagram illustrating an interworking environment 200to which the present invention may be applied, according to anillustrative embodiment of the present invention. The interworkingenvironment 200 includes a first radio access network 210, which in theillustrative embodiment is a 3G network, and second radio access networkareas 220, which in the illustrative embodiment are WLANs, dispersedthere through. A mobile terminal 100 moves through coverage areas of thefirst and second radio access networks, possibly including areas of dualcoverage. A server 270, accessible from both the first radio accessnetwork 210 and the second radio access network 220, functions as asource from which a video program can be downloaded to the mobileterminal 100.

A detailed description of a first illustrative embodiment of the presentinvention will now be given with respect to FIGS. 3 and 4. The followinggeneral description applies to an interworking that includes a 3Gcellular network and a WLAN, where the 3G cellular network has a slowerdata transfer rate than the WLAN. However, as noted above, the presentinvention may be employed with respect to more than two networks andwith other different networks, all while maintaining the spirit andscope of the present invention.

Once in a WLAN cell, a Mobile Terminal (MT) attaches to the WLAN usingestablished protocols and methods, and starts downloading the videocontent to local storage using WLAN access. Given the discrepancybetween the downloading rate and the playback rate, after some time haselapsed from the start of downloading, the MT will have a certain amountof buffered video.

We can then take advantage of this buffered amount to increase the videodisplay quality with the assurance that it will not drop

For illustrative purposes, the following notations are employed herein:

Buffered amount: B_(t)

Data transfer rate in the 3G coverage area: R_(g)

Playback rate: R_(p)

Time duration for the rest of the video: T

Moreover, the following constraint is employed:(R _(p) −R _(g))*T←B _(t)

Advantageously, the present invention ensures that once the videodisplay quality (video playback rate) is increased while within range ofthe WLAN coverage, the video quality will not fall back for theremainder of the video session even if the mobile terminal moves backinto lower data rate 3G coverage. The original playback rate isdesignated herein as R_(g). At a given moment when the MT is downloadingin a WLAN cell, the buffered amount is B_(t) and the time duration forthe remainder of the unplayed video is T, the MT can make the followingworst-case calculation. Assuming that the MT would immediately leave thecoverage range of the WLAN cell and would not enter the coverage rangeof a WLAN cell again for the remainder of the video session, the maximumplayback rate that we can upgrade to is as follows:R _(p) =B _(t) /T+R _(g)Thus, when downloading is continued, the playback rate can be safelyupgraded and once upgraded, the rate will not drop even if the MT movesout the WLAN cell immediately after the upgrade and remains in the 3Gcoverage for the remainder of the session.

Advantageously, the present invention employs layered coding to providethe above advantages and features. That is, the stored video is codedinto multiple layers. For illustrative purposes, the followingdesignations and constraints are employed: the base layer has rate R₀;each additional layer adds ΔR_(i, i=0,1, . . . n); ΔR_(i)<R_(g); ad thecurrent playback rate is R_(k). These rates may be determined in variousways, including, but not limited to, based on information included withthe downloaded program data, based on information transmitted from theradio access networks separately from the downloaded program data, basedon previous downloads, and based on predetermined rates.

When the MT is downloading in a WLAN cell, it checks the downloadedamount and the residual time of the video session, and as soon as thedownloaded amount can make R_(p) safely jump to R_(k)+ΔR_(k), the MTstarts downloading the next layer along with the current layer(s) andthe playback rate is upgraded to R_(k)+ΔR_(k). This upgraded playbackrate (video display quality) will be sustained throughout the remainderof the video session. Thus, even if the mobile terminal immediatelyleaves the coverage area of a WLAN cell and immediately returns to thecoverage area of the 3G cellular network after the playback rate hasjust been updated, the upgraded playback rate will be maintained duringthe duration of the playing back of the video program.

FIG. 3 is a flow chart illustrating the steps for downloading anddisplaying a video program using a mobile terminal in an interworkingenvironment according to a first illustrative embodiment of the presentinvention. In the illustrative embodiment of the FIG. 3, the first radioaccess network has a first data transfer rate and the second radioaccess network has a second data transfer rate that is faster than thefirst data transfer rate.

It is determined whether the mobile terminal has entered a coverage areaof the second radio access network (step 305). If so, the mobileterminal attaches to the second radio access network and beginsdownloading the video program at the second (faster) data transfer rate(step 310).

It is to be appreciated that the mobile terminal may or may not havebeen in the coverage area of the first radio access network anddownloading the video program in that area (at the first (slower) datatransfer rate) prior to entering the coverage area of the second radioaccess network as determined at step 305. That is, the present inventiondoes not require any particular or pre-specified sequence of movementsby the mobile terminal through the various networks to obtain thebenefits of the present invention. All that is necessary is that themobile terminal is able to detect and utilize the first and second radioaccess networks that interwork to download a particular program.

The downloaded video program is displayed on the mobile terminal at aplayback rate that corresponds to a predetermined display quality (step315). Excess portions of the downloaded video program (that result whena rate at which the video program is downloaded exceeds thepredetermined playback rate) are buffered (step 320).

It is then determined whether the buffered excess portions of thedownloaded video program exceed a threshold value (step 325). If so,then the method proceeds to step 330. Otherwise, the method returns tostep 310.

The threshold value employed at step 325 may be equal to, for example,the time duration of the remainder of the video program to be playedback multiplied by the difference between the playback rate and thefirst data transfer rate. Using the nomenclature defined above, thethreshold as previously described may be represented as follows:threshold=T*(R _(p) −R _(g))

The threshold value corresponds to that value where sufficient excessprogram portions have been stored in the buffer such that the higherplayback level can be maintained for the duration of the program even ifthe data transfer rate fall to the lower rate for the time remaining inthe program. This threshold value may be calculated periodically orcontinuously during the course of the playback as desired. Variousthreshold values may be set based on the numbers of layers available todetermine at which point the playback may be increased from one layer tothe next. For example, if the program comprises 5 layers, respectivethresholds may be determined to increase the playback from a firstplayback rate to a second rate, and then from a second rate to a thirdrate, and so forth. In each case, once the playback level has beenincreased to the next rate, playback remains at least at that rateregardless of the download data transfer rate.

At step 330, the number of layers being downloaded is increased, and theplayback rate at which the video program is displayed is increased so asto increase the display quality. For each additional layer beingdownloaded, the playback rate may be increased to a value that is equalto the sum of the current playback rate and an incremental playback rateincrease corresponding to that additional layer. It is to be appreciatedthat step 330 may optionally include the step of transmitting a requestfrom the mobile terminal to a source of the video program for the sourceto increase the number of layers being broadcast to the mobile terminal.

It is to be appreciated that the amounts of increase, both to the numberof layers and to the playback rate, are dependent upon the amount of thebuffered excess portions of the downloaded video program as well as thetime duration of the remainder of the video program to be played back.Further, the increase to the playback rate is based upon which layersare being downloaded since, as noted above, each layer adds anincremental change to the playback rate (and hence an incremental changeto the video display quality).

It is determined whether the mobile terminal has left the coverage areaof the second radio access network and is within the coverage area ofthe first radio access network (step 335). If not, then the methodreturns to step 310. Otherwise, the current playback is maintained whilethe downloading of the video program returns to the first data transferrate (step 340). It is to be appreciated that the current playback rateis maintained irrespective of whether the mobile terminal stays withinthe coverage area of the first data network for the duration of theplayback or the downloading of the video program. Moreover, it should benoted that the downloading or streaming rate in the slower network(i.e., the first radio access network) should be greater than the raterequired by the additional layer(s).

FIG. 4 is a diagram illustrating the downloading of a layered media 400with respect to data transfer rate versus time, according to the firstillustrative embodiment of the present invention.

The layered media includes multiple layers which are downloaded at thedata transfer rate R_(g) in the 3G coverage area and at a data transferrate R_(w) in the WLAN coverage area. The playback rate is intended toincrease with the downloading of each subsequent layer as describedabove with respect to FIG. 3. As such the playback rate R_(o) for thebase layer is less than the playback rate for subsequent layer(s) R_(i).

A description of a second illustrative embodiment of the presentinvention will now be given with respect to FIGS. 5 and 6. In the secondillustrative embodiment, the mobile terminal starts downloading anadditional layer as soon as the mobile terminal enters the fasternetwork (e.g., the WLAN), and the playback rate (display quality) isupgraded when the rest of the whole additional layer is downloaded inthe WLAN. The base layer is generally larger than any of the additionallayers, and the faster network (e.g. WLAN) has far greater throughputthan the slower network (e.g. cellular). Thus, it is possible to finishdownloading the entire additional layer within the faster network. Asnoted above, the layered media need not follow the physical sizeconstraints with respect to the layers thereof as shown in FIGS. 4 and 6and, thus, other structures may be employed for the layered media whilemaintaining the spirit and scope of the present invention. For example,each subsequent layer need not be smaller in size than the precedinglayer.

One advantage of this embodiment is that the additional layer may notneed to be available in the slower network (e.g., in the case whendifferent layers are broadcast in different types of wireless networks).

FIG. 5 is a flow chart diagram illustrating steps for downloading anddisplaying a video program using a mobile terminal in an interworkingenvironment according to a second illustrative embodiment of the presentinvention. In the illustrative embodiment of the FIG. 5, the first radioaccess network has a first data transfer rate and the second radioaccess network has a second data transfer rate that is faster than thefirst data transfer rate. Further, the video program is encoded intomultiple layers.

A layer of the video program is downloaded, via the first or secondradio access network, wherein the layer is downloaded at the faster datatransfer rate when the mobile terminal is within the coverage area ofthe second radio access network (step 505).

The downloaded video program is displayed on the mobile terminal at aplayback rate that corresponds to a predetermined display quality (step510).

It is determined whether the mobile terminal has entered a coverage areaof the second radio access network (step 515). If so, then the mobileterminal begins downloading a next layer of the video program, even if acurrent, or preceding, layer of the video program is still beingdownloaded, with the layers being downloaded at the second (faster) datatransfer rate (step 520). Otherwise, the method returns to step 505.

With respect to step 520, the next layer is preferably downloadedstarting at a current playback point. In this way, continuity ismaintained with respect to the content being played back.

It is then determined whether the next layer that commenced downloadingat step 520 has been completely downloaded (step 525). If so, then theplayback rate at which the video program is displayed is increased so asto increase the display quality (step 530). Otherwise, the methodreturns to step 525.

It is to be appreciated that the increase to the playback rate is basedupon which layer(s) is being downloaded since, as noted above, eachlayer adds, when applicable, an incremental change to the playback rate(and hence an incremental change to the video display quality).

It is determined whether the mobile terminal has left the coverage areaof the second radio access network and is within the coverage area ofthe first radio access network (step 535). If not, then the methodreturns to step 520. Otherwise, the current playback is maintained (step540). It is to be appreciated that the current playback rate ismaintained irrespective of whether the mobile terminal stays within thecoverage area of the first data network for the duration of the playbackor the downloading of the video program.

FIG. 6 is a diagram illustrating the downloading of a layered media 600with respect to data transfer rate versus time, according to the secondillustrative embodiment of the present invention.

The layered media includes multiple layers which are downloaded at thedata transfer rate R_(g) in the 3G coverage area and at a data transferrate R_(w) in the WLAN coverage area. The playback rate is intended toincrease, when applicable, with the downloading of each subsequent layeras described above with respect to FIG. 3.

Advantageously, the present invention can provide a constant videoquality increase as the direct benefit of “occasionally crossing” WLANcells. Moreover, the present invention advantageously does not require adetermination of how long the mobile terminal will be inside the WLANcells.

Although the illustrative embodiments have been described herein withreference to the accompanying drawings, it is to be understood that thepresent invention is not limited to those precise embodiments, and thatvarious other changes and modifications may be affected therein by oneof ordinary skill in the related art without departing from the scope orspirit of the invention. For example, although the present embodimentsare described with reference to video programs, it is clear that thepresent invention is applicable to audio programs, and other multimediaprograms that may be downloaded through radio access networks. All suchchanges and modifications are intended to be included within the scopeof the invention as defined by the appended claims.

1. A method for downloading and displaying a program using a mobileterminal in an interworking environment that includes a first radioaccess network having a first data transfer rate and a second radioaccess network having a second data transfer rate that is faster thanthe first data transfer rate, the method comprising the steps of:downloading, via the first or second radio access networks, a layer of aprogram encoded into multiple layers, the program being downloaded atthe second data transfer rate when the mobile terminal is in thecoverage area of the second radio access network; displaying thedownloaded video program at a playback rate that corresponds to adisplay quality; buffering excess portions of the downloaded programthat result when a rate at which the video program is being downloadedexceeds a rate at which the video program is displayed; and increasingthe number of layers being downloaded, and the playback rate at whichthe video program is displayed to thereby increase the display quality,when the buffered excess portions of the downloaded program exceeds athreshold level.
 2. The method of claim 1, wherein the threshold levelcorresponds to a time duration of a remainder of the program to beplayed back multiplied by a difference between a current playback rateand the first data transfer rate.
 3. The method of claim 1, wherein theincreasing step comprises the step of limiting the playback rate to amaximum value that is equal to a sum of the first data transfer rate anda quotient resulting from dividing the buffered excess portions of thedownloaded program by a time duration of the remainder of the program tobe played back.
 4. The method of claim 1, wherein the increasing stepcomprises increasing the playback rate by an amount that corresponds tothe number of layers being downloaded, such that each additional layerbeing downloaded results in an incremental change to the playback rate.5. The method of claim 1, further comprising the step of continuing todownload the program from the first radio access network whilemaintaining a last playback rate from the second radio access networkfor a duration of playing back the program, when the mobile terminal isagain within the coverage area of the first radio access network.
 6. Themethod of claim 1, further comprising the step of maintaining a lastplayback rate from the second radio access network for a duration ofplaying back the layered media, when the mobile terminal is again withinthe coverage area of the first radio access network and the entireprogram has been completely downloaded.
 7. The method of claim 1,wherein the increasing step comprises the step of transmitting to asource of the program a request to increase the number of layers beingtransmitted.
 8. The method of claim 1, wherein the first radio accessnetwork is a 3G network and the second radio access network is aWireless Local Area Network (WLAN).
 9. A mobile terminal for downloadingand displaying a program in an interworking environment that includes afirst radio access network having a first data transfer rate and asecond radio access network having a second data transfer rate that isfaster than the first data transfer rate, the mobile terminalcomprising: a receiver for downloading, via the first or second radioaccess networks, a layer of a program encoded into multiple layers, theprogram being downloaded at the faster data transfer rate when themobile terminal is in the coverage area of the second radio accessnetwork; a display for displaying the downloaded video program at aplayback rate that corresponds to a display quality; a memory device forbuffering excess portions of the downloaded program that result when arate at which the program is being downloaded exceeds a rate at whichthe video program is displayed; and a processor, coupled to thereceiver, display and memory device, for increasing the number of layersbeing downloaded, and the playback rate at which the program isdisplayed to increase the display quality, when the buffered excessportions of the downloaded program exceeds a threshold level.
 10. Themobile terminal of claim 9, wherein the threshold level corresponds to atime duration of a remainder of the video program to be played backmultiplied by a difference between the playback rate and the first datatransfer rate.
 11. The mobile terminal of claim 9, wherein the processorlimits the playback rate to a maximum value that is equal to a sum ofthe first data transfer rate and a quotient resulting from dividing thebuffered excess portions of the downloaded program by a time duration ofthe remainder of the program to be played back.
 12. The mobile terminalof claim 9, wherein the processor increases the playback rate by anamount that corresponds to a number of layers being downloaded, suchthat each additional layer being downloaded results in an incrementalchange to the playback rate.
 13. The mobile terminal of claim 9, whereinthe receiver continues to download the program from the first radioaccess network while the processor maintains a last playback rate fromthe second radio access network for a duration of playing back theprogram, when the mobile terminal is again within a coverage area of thefirst radio access network.
 14. The mobile terminal of claim 9, whereinthe processor maintains a last playback rate from the second radioaccess network for a duration of playing back the layered media, whenthe mobile terminal is again within a coverage area of the first radioaccess network and the program has been completely downloaded.
 15. Themobile terminal of claim 9, further comprising a transmitter fortransmitting to a source of the program a request to increase the numberof layers being transmitted, in respond to a command issued by theprocessor.
 16. The mobile terminal of claim 10, wherein the first radioaccess network is a 3G cellular network and the second radio accessnetwork is a Wireless Local Area Network (WLAN).
 17. A method fordownloading and displaying a program using a mobile device in aninterworking environment that includes a first radio access networkhaving a first data transfer rate and a second radio access networkhaving a second data transfer rate that is faster than the first datatransfer rate, the method comprising the steps of: downloading, via thefirst or second radio access networks, a layer of a video programencoded into multiple layers, the video program being downloaded at thefaster data transfer rate when the mobile terminal is in the coveragearea of the second radio access network; displaying the downloaded videoprogram at a playback rate that corresponds to a display quality;downloading a current layer and a next layer of the video program at thesame time when the mobile terminal enters the coverage area of thesecond radio access network; and increasing the playback rate at whichthe video program is displayed to increase the display quality, when thenext layer has been completely downloaded.
 18. The method of claim 17,wherein the multiple layers comprise a base layer and at least onesubsequent layer, each of the at least one subsequent layer beingassociated with an incremental change to the playback rate, and whereinsaid increasing step increases the playback rate by an amount thatcorresponds to the next layer.
 19. The method of claim 17, furthercomprising the step of continuing to download the video program from thefirst radio access network while maintaining a last playback rate fromthe second radio access network for a duration of playing back the videoprogram, when the mobile terminal is again within the coverage area ofthe first radio access network.
 20. The method of claim 17, furthercomprising the step of maintaining a last playback rate from the secondradio access network for a duration of playing back the layered media,when the mobile terminal is again within the coverage area of the firstradio access network and the entire video program has been completelydownloaded.
 21. The method of claim 17, wherein the second downloadingstep comprises downloading the next layer starting from a currentplayback point.
 22. The method of claim 19, wherein the first radioaccess network is a 3G cellular network and the second radio accessnetwork is a Wireless Local Area Network (WLAN).
 23. A mobile terminalfor downloading and displaying a video program in an interworkingenvironment that includes a first radio access network having a firstdata transfer rate and a second radio access network having a seconddata transfer rate that is faster than the first data transfer rate, themobile terminal comprising: a receiver for downloading, via the first orsecond radio access networks, a layer of a video program encoded intomultiple layers, the video program being downloaded at the faster datatransfer rate when the mobile terminal is in the coverage area of thesecond radio access network, the receiver downloading a current layerand a next layer of the video program at the same time when the mobileterminal enters the coverage area of the second radio access networkeven if a preceding layer of the video program is still beingdownloaded; a display for displaying the downloaded video program at aplayback rate that corresponds to a display quality; and a processor,coupled to the receiver, and display, for increasing the playback rateat which the video program is displayed to thereby increase the displayquality when the next layer has been completely downloaded.
 24. Themobile terminal of claim 23, wherein the multiple layers comprise a baselayer and at least one subsequent layer, each of the at least onesubsequent layer being associated with an incremental change to theplayback rate, and wherein the display increases the playback rate by anamount that corresponds to the next layer.
 25. The mobile terminal ofclaim 23, wherein the processor maintains a last playback rate from thesecond radio access network for a duration of playing back the videoprogram, when the mobile terminal is again within a coverage area of thefirst radio access network.
 26. The mobile terminal of claim 23, whereinthe processor maintains a last playback rate from the second radioaccess network for a duration of playing back the layered media, whenthe mobile terminal is again within a coverage area of the first radioaccess network and the entire video program has been completelydownloaded.
 27. The mobile terminal of claim 23, wherein the receiverdownloads the next layer of the video program starting from a currentplayback point.
 28. The mobile terminal of claim 23, wherein the firstradio access network is a 3G cellular network and the second radioaccess network is a Wireless Local Area Network (WLAN).